Paving or binder compositions containing asphalt reacted with diisocyanate

ABSTRACT

Compositions suitable for use as paving or as a binder for paving materials and possessing improved ductility, viscosity and resistance to oxidation are obtained by reacting a minor amount of a diisocyanate with asphalt. The preferred diisocyanate is toluene diisocyanate. This composition may be blended with urethane in situ or the urethane-forming components, e.g., polyhydroxy-terminated polydiene and hydrocarbon diisocyanate may be added separately. Blending the asphalt-diisocyanate composition with urethane-forming materials has been found to improve viscosity and homogeneity and decrease the amount of carbon tetrachloride insolubles.

United States Patent Fauber [451 Mar. 21, 1972v [54] PAVING OR BINDER COMPOSITIONS CONTAINING ASPHALT REACTED v WITH DIISOCYANATE 106/123 TD; 208/22, 44; 260/28, 285 AS, 77.5 A, 77.5 AM, 77.5 CH, 858, 859, 77.5 CR

[56] References Cited UNITED STATES PATENTS 3,084,182 4/1963 McElroy ..106/273XN 3,092,594 6/1963 Helss ..260/28 X 3,179,610 4/1965 Wood ..260/28 3,182,032 5/1965 Charlton et a1. 106/273 X N 3,358,052 12/1967 Archer, Jr. et a1. ..260/28 X 3,427,366 2/1969 Verdol et a1 ..260/77.5 CR

Primary Examiner-Joan B. Evans Attorney-McLean and Morton [5 7] ABSTRACT Compositions suitable for use as paving or as a binder for paving materials and possessing improved ductility, viscosity and resistance to oxidation are obtained by reacting a minor amount of a diisocyanate with asphalt. The preferred diisocyanate is toluene diisocyanate. This composition may be blended with urethane in situ or the urethane-forming components, e.g., polyhydroxy-terminated polydiene and hydrocarbon diisocyanate may be added separately. Blending the asphalt-diisocyanate composition with urethane-forming materials has been found to improve viscosity and homogeneity and decrease the amount of carbon tetrachloride insolubles.

6 Claims, No Drawings PAVING OR BINDER COMPOSITIONS CONTAINING ASPHALT REACTED WITH DII SOCYANATE It is considered desirable that asphalts used in paving roads have three test' properties: high ductility at low temperature, high viscosity at high temperature, and good resistance to oxidation. High ductility at low temperature is important to prevent cracking of the pavement during cold weather. High viscosity on the other hand, is of significant importance during hot summer weather in order to provide stability to the road surface. Oxidation of asphalt produces surface hardening which decreases the durability of roads made with the asphalt.

In accordance with the present invention, it has been found that normally solid, including semi-solid asphalts which have been reacted with a small amount of diisocyanate possess improved properties of ductility, viscosity and resistance to oxidation. The particular asphalt used may depend largely on the properties desired in the final product and the asphalts may be cutback with other hydrocarbon oils. For example, if low temin liquid form can be blended into the fluid asphalt in an amount sufficient to produce the desired improvement in low temperature ductility and viscosity at 140 F. The actual amount of diisocyanate added will often be from about 0.05 to 2 weight percent or more, preferably from about 0.2 to l percent, based on the asphalt. Blending of the components may, for example be carried out in a propeller-type mixer in which the temperature is held at the desired level for the duration of the mixing, which may, for example, be about one-half hour.

Asphalt compositions prepared in the above or similar manner were found to have properties of high ductility at low temperature, high viscosity at high temperature and resistance to oxidation superior to those of asphalts not reacted with diisocyanates. Resistance to oxidation was determined largely by subjecting the samples to The Thin Film Oven Test (T- FOT). This test simulates the conditions which asphalt will encounter in a hot mix plant pug mill and measures the change in properties of the asphalt due to this exposure. Accordingly an approximately Aa-inch-thick film of asphaltic material is heated in an oven for 5 hours at 325 F. The change in penetration (as percent of the value before heating) is then determined.

Table I lists data derived from comparisons of untreated asphalts of two types, i.e., Mid-Continent and Wyoming, and also compares the we treated asphalts with two untreated asphalts having the same penetration. In both cases (Runs 2 and 5)0.47 weight percent of tolylene diisocyanate (TDl) was reacted with the asphalt using the exemplary procedures described previously for mixing.

TABLE I Runs Midcontinent Wyoming Midcontinent asphalt, same Wyoming asphalt, same asphalt A penetration as asphalt B penetration as Midcontnient reacted with 2 by Vacuum Wyoming reacted with 5 by vacuum asphalt A 'IDI reduction asphalt B TDI reduction Specific gravity at 60 F 1. 0168 1.0300 Duotility at 392 F... 1. 3 9. 0 1.1 1. 5 3 Ductility at 77 F 100+ 100+ 100+ 100+ 100+ 100+ Softening point (RdzB), F" 118 123 119 119 124 119 Penetration at 77 F 63 55 55 51 51 50 Penetration at 32 F c 18 18 14 12 13 Viscosity at 275 F., {101508. 98 45 420 250 268 250 Kin. at 140 F., (LP 2, 196 2, 586 2, 312 1, 453 1, 870 1, 460 Sliding pinto at 60 F., .05/sec., megapoises 13 27 18 20 42 'IFOT, 5 hrs. at 325 F.:

Penetration at 77 F. alter test 39 40 35 32 37 32 Percent penetration retained 71 64 63 63 74 64 perature ductility is desired, asphalts having a penetration of up to about 80 are advantageously employed, though it is to be understood that good low temperature ductility may also be obtained when the penetration of the asphalt exceeds 80. Particularly good viscosity at 140 F. is found when asphalts of about 20 to 300 or greater penetration are used.

The isocyanate employed to produce the asphalt compositions of this invention may be any one or more ofa number of materials containing essentially two isocyanate radicals although a minor portion of the material may have more than two isocyanate radicals. The usable agents for making the composition of this invention include the various organic or hydrocarbon diisocyanates such as the aliphatic, including cycloaliphatic, and aromatic diisocyanates. Preferably the diisocyanates have about six to 18 carbon atoms. Examples of these materials are tolylene diisocyanates (TDI), 4,4-diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, phenylene diisocyanates, trans-vinylene diisocyanate, 3,3- dimethoxy-4,4-biphenyl diisocyanate, as well as related aromatic and aliphatic diisocyanates, which may also be substituted with other organic or inorganic groups g Mixing or blending of the asphalt and the diisocyanate is conveniently carried out by first heating the asphalt to a liquid state, e.g., to a temperature of from at least about 200 F. to just below the temperature at which the diisocyanate decomposes preferably from about 225 to 350 F. The diisocyanate Comparing Column 1 with Column 4 in Table 1 shows the two base asphalts are quite different. The Mid-Continent A (Col. 1) possesses low specific gravity and high viscosity and the Wyoming B (Col. 4) possesses high specific gravity and low viscosity.

Comparing Column 1 with Column 2 and Column 4 with Column 5 shows that the reaction with TDI produces quite significant changes in properties. These changes are due to chemical reaction, because if the TDI simply diluted the asphalt, higher penetrations and lower viscosities would have resulted, whereas the opposite effect is clearly shown. Also this comparison shows the desirable effects of increased low temperature ductility, increased viscosity at F. and improved Thin Film Oven Test (TFOT) results of increased percent retained penetrations.

Comparisons of Column 2 with Column 3 and Column 5 with Column 6 show the desirable improvements cannot be obtained by simply vacuum reducing the crude asphalt to the same penetration as that of the TDI reaction product.

It is of particular significance that Wyoming asphalt made by vacuum reduction when untreated with diisocyanate could not meet the Asphalt lnstitutes recommended viscosity specification for AC-24 paving asphalt, however, the product obtained by reacting the asphalt with 0.47 weight percent of toluene diisocyanate surpassed these requirements with ease as shown in Table II.

TABLE II ing 100 parts of butadiene in the presence of 35 parts of isopropanol and 6 parts of hydrogen peroxide for 2% hours at l30 C.; Styrene copolymer No. 15 which has a molecular Remit) weight of about 2,200-2,500, a viscosity at 30 C. of 250 Asphalt Unnamed product poises, a hydroxyl content (meq./g.) of 0.95, a hydroxyl Institute Wyoming Asphalt number of53 mg. KOH/g. about 2.5 terminal, allylic, hydroxyl Rmge groups which are predominantly primary, and an iodine number of 335, and which can be made by polymerizing 75 -f" 1460 1870 parts butadiene and 25 parts styrene in the presence of 70 zil F 700+ 250 268 1 parts isopropanol and 10 parts of 50 percent hydrogen peroxcentipoiscs b ide for 2% hours at 120 C.; Acrylonitrile copolymer No. l5, Vis. at 60 F., 100- 22 42 which has a viscosity of 550 poises at 30 C., a hydroxyl content of 0.80 meq./g., and hydroxyl number of 45 mg. KOH/g, an average molecular weight of 2,5003,000, about 2.5 terminal, allylic hydroxyl groups, which are predominantly primary, and an iodine number of 345, and which can be made It has been found that the asphalt composition of this invenby copolymerizing acrylonmne with buladiene isopiopanol tion, in addition to having utility, for instance, as a paving i l l l and f Presence gg g pfigxlde l g the material, also may subsequently be blended with urethane- 0 l tg lratlgoo reactants. pints uta iene, h pans forming compounds, e.g., poly-hydroxyl-containing polydiene acry 9 pans lsopmpano 10 percent ydrogen polymers and additional diisocyanate, to form a composition gzt gi made usin a SW60 emanation avin as h It having further enhanced viscosity, improved homogeneity and and a 6mm enetratig avin halt 5 1 g a less carbon tetrachloride insolubles. The polyhydroxyl as halts were i n ixed O 2 h l i ht polydiene polymers include hydroxyl-terminated polybu- 6;1t toluene diisoc anate at a mn; rature Of'2l0 250 3 F [mime having on average about to predomb This treated asphalt was stored at 275 F. for 7 days and then nanny primary i i i hydi-oxyl groups per tested. After testing, hydroxy-terminated polybutadiene 45 .moleculc polydiene and additional duocyanate. may be (previously described) and additional toluene diisocyanate mcorpormed m Small amounts Sufficient to from were added simultaneously at a temperature of 210-250 F. about 0.5 to 6 percent urethane in the asphalt composition of and in proportion to and in amounts sumciem to provide an this invemion and in proportions to give an NCO/OH ratio NCO/OH ratio of 1.0 and 3 weight percent of urethane. Also between about 0.6 to l.2. The diisocyanate can be of the types 0'35 Weight percent based on the urethane of Stannous prevlously described harem toate was added as a catalyst. After 7 days additional storage Exemplary of the hydroxyl'cfmammg polybutadlene at 275 F., the blends were again tested. For comparative purcopolymers and homopolymers Whlch may be employed are poses /60 and /70 penetration asphalts were also the followmg: Y polybumdlene prepared containing 3 weight percent of urethane alone. This homopolymer having Scoslty of 50 Polses at 300 a was done by first adding hydroxyl-terminated polybutadiene hydroxyl Content of meqjg't a hylroxyl number oil 45 and heating to 210250 F. Stannous octoate catalyst Ev of an average molecular Welght of 2209-2500 40 (0.35 wt. based on urethane, and sufficient toluene diisoabout 2.l2.2 terminal, allylic, hydroxyl groups which are Cyanate to give an NCO/OH ratio of L0 were then added Predominantly P y and an iodine number of 3981 and After storage at 275 F. for 7 days, the blend was tested. which can be P p y polymerizing Parts of buladiene Tables III and IV compare the properties of the untreated the Presence of 70 P of isopropanol and 10 Parts of asphalt, the asphalt containing only urethane, the asphalt hydrogen peroxide in an aluminum clad autoclave al 1 4 treated with varying amounts of TDI and the asphalt treated for 2 hours; Polybutadiene No. 15, a homopolymer having a i h TD] to hi h urethane was dd d Comparing h viscosity at 30 C. of 200 poises, a hydroxyl content of 0.80 Ki i vi i i (KV) at 140 F, f l i may b mq-/g-. a hydroxy number of 45 g- /g-. an average seen that in the case of the 50/60 penetration asphalt sample l ular weight of 3,0003,500, about 2.6 terminal allylic (Table III) almost a nine fold increase results and in the case hydroxyl groups which are predominantly primary and an 50 of the 60/70 penetration sample (Table IV) almost a seven iodine number of 395, and which can be made by polymerizfold increase was found.

TABLE III 50/60 penetration asphalt 3% urethane forming components added after 'ID1 Asphalt Percent TDI prctrcat percent Untreated containing asphalt 3% urethane 0.25 0.50 1,0 0,25 0.50 1.0

Penetration at 77 F 51 63 45 44 39 43 43 33 Softening point (R&B) F 113 126 129 133 135 Oliensis Spot, AO.

After 24 hours .055.021. 33. I I i i i Buctility at 77251111: 100+ 100+ 100+ 100+ 100+ 100+ 100+ 100+ Ki 5ii4 o ?'c.P:IiIj "1,1151 '1540'"fi5i""','i""'50s? gia' tfii""'iji Furol vis. at 275 F., 500.. 125 117 1 537 204 228 406 Specific gravity at 00 F. 1. 0300 1, 0336 1. 0387 1. 0392 1.0370 1.0345 1. 0388 1. 0356 TFO'I, \vt. percent loss .10 .18 .15 1.0 .21 .07 .08 .08 Penetration after TFOT 32 35 34 30 32 27 2G 22 Percent retained penetration 63 56 76 68 82 G3 01 67 31 21 .68 .80 1. 28 .52 41 54 111501, in G014, wt. percent TABLE IV 60/70 penetration asphalt 3% urethane forming components added after TDI Asphalt Percent 'IDI pretreat percent Untreated containing asphalt 3% methane 0.25 0.50 1.0 0.25 0.50 1.0

Penetration at 77 F 69 79 52 53 46 50 57 44 Soften n point (R&B), 120 115 124 124 128 130 131 140 011811515 Spot, A

After 24 hours xylene, A0

tter 24 hours Ductility at 77 F 100+ 100+ 100+ 100+ 100+ 100+ Duetility at 39.2 F 5. 7 5. 5 5. 5. 2 6. 0 4. 0

KV at 140 F., C.P 3500 3350 12040 5474 5209 14015 Furol v15. at 275 F., sec. 226 225 304 338 356 622 speclfic gravlty at 000 F 1. 0150 1. 0211 1. 0224 1. 0150 1. 0191 1. 0203 1. 0207 1. 0231 Loss, TFOT, wt., percent .0 .03 .06 .04 .05 .06 0. 6 .05

Penetration after TFOI 39 49 36 34 33 34 34 28 Percent Retained Penetration. '67 62 69 64 72 68 60 64 Insol, in 0014, wt: percent .2 64 .51 .39 1. 29 51 31 56 1 Gain.

The sequence of addition of the various components is imever, the blend obtained by mixing the components in this portant and different results are observed when the urethane sequence will not necessarily have the same properties as components are added at the same time as the isocyanate used those found when forming the urethane in the presence of the for pretreating the asphalt. Most significantly there is an iny ee ed asphal crease in penetration and a decrease in viscosity over the II 15 Clalmedi results observed when the urethane components are added A composltlon consisting essemlany of the reactlol'l subsequent to the treatment with the diisocyanate alone. Product 0f asphalt and a Small amount of about to 2 P Th results are b l d i T bl V cent by weight based on the asphalt of a hydrocarbon diisocyanate having about six to 18 carbon atoms, said amount TABLE V being sufficient to produce improved properties of at least one of viscosity, ductility, and resistance to oxidation of the asphalt, having added thereto subsequent to the reaction of 50/60 Pen Asphalt the hydrocarbon diisocyanate with the asphalt, small amounts of a hydrocarbon diisocyanate of about 6 to 18 carbon atoms Treated with 0.25% 3% urethane Addition and a hydroxyl-terminated polybutadiene oil having about 2.1 Prior 3% gFf Plus 015% "S to 2.6 predominantly primary, allylic, terminal hydroxyl M mp groups per molecule, said subsequently added hydrocarbon nsocyanate and hydroxyl-terminated polybutadiene oil bemg P sufficient to produce about 0.5 to 6 percent urethane.

en. at 77 F. 43 55 Softening Pt. 133 123 2. The composition of claim 1 1n WhlCh the amount of (11150- (R&B). F. cyanate is from about 0.2 to 1 percent by weight. 8: 3. The composition of claim 2 in which the diisocyanate is i m 204 155 toluene diisocyanate.

275" F.. sec, 4. The composition of claim 1 in which the ratio of NCO to OH in the subsequently added diisocyanate and hydroxyl-ter- 45 minated polybutadiene oil is between about 0.6 and 1.2.

Rather than adding the urethane components separately, The fompositiol'l of claim 4 in whlch the diisocyanate of subsequent to the diisocyanate pretreatment, it is also contemtoluene y at 4 u l d h premixgd h f i Components may b 6. The composition of claim 1 in which the diisocyanate is added so long as the resulting polymer has not cured to the toluene diisocyanatepoint where it is no longer compatible with the asphalt; how 1 

2. The composition of claim 1 in which the amount of diisocyanate is from about 0.2 to 1 percent by weight.
 3. The composition of claim 2 in which the diisocyanate is toluene diisocyanate.
 4. The composition of claim 1 in which the ratio of NCO to OH in the subsequently added diisocyanate and hydroxyl-terminated polybutadiene oil is between about 0.6 and 1.2.
 5. The composition of claim 4 in which the diisocyanate of toluene diisocyanate.
 6. The composition of claim 1 in which the diisocyanate is toluene diisocyanate. 